Here are some of the highlights of the changes from version 2.1 RC1 (please see the Release Notes in the distribution for complete details)

* RtuTraverse API changes (your application will need to be recompiled) This API is currently in Beta. o Automatic fallback to CPU when no NVIDIA GPU is present o Sped up CPU fallback path o See documentation for new capabilities, including optional return data for ray hits o Added missing traversal sample * The OptiX libraries no longer link against nvcuda.dll or nvcuda.so. This allows apps linking to OptiX to execute on machines that do not have an NVIDIA driver installed. This also enables the the CPU fallback option of rtuTraverse. * Sped up SBVH builds up to 2x * Fixed bug on G80 GPUs where it complained about cuMemAlloc

You got 0.53fps at 9999 running "Swimming Shark" and it's bad because your videocard wasn't stress with ~40%!?! of GPU usage due to your CPU 100% load on single core/thread. lool! Default for this sample is recommended.